Editing BOOMERanG experiment

{{Short description|High-altitude balloon package measuring the universe's geometry}}
{{Infobox telescope}}
{{Cosmology|experiments}}
'''BOOMERanG experiment''' ('''Balloon Observations Of Millimetric Extragalactic Radiation And Geophysics''') was an experiment that flew a telescope on a [[high-altitude balloon|(high-altitude) balloon]] and measured the [[cosmic microwave background radiation]] of a part of the sky during three sub-orbital flights. It was the first experiment to make large, high-fidelity images of the CMB temperature anisotropies, and is best known for the discovery in 2000 that the geometry of the universe is close to flat,<ref name="Nature_27Apr00">{{cite journal|last1=de Bernardis|first1=P.|display-authors=etal|journal=Nature|date=27 April 2000|volume=404|issue=6781|pages=955–959|doi=10.1038/35010035|arxiv=astro-ph/0004404 | title=A Flat Universe from High-Resolution Maps of the Cosmic Microwave Background Radiation|pmid=10801117|bibcode = 2000Natur.404..955D |s2cid=4412370}}</ref> with similar results from the competing [[Millimeter Anisotropy eXperiment IMaging Array|MAXIMA]] experiment.

By using a telescope which flew at over 42,000 meters high, it was possible to reduce the atmospheric absorption of microwaves to a minimum. This allowed massive cost reduction compared to a satellite probe, though only a tiny part of the sky could be scanned.

The first was a test flight over [[North America]] in 1997. In the two subsequent flights in 1998 and 2003 the balloon was launched from [[McMurdo Station]] in the Antarctic. It was carried by the [[Polar vortex]] winds in a circle around the [[South Pole]], returning after two weeks. From this phenomenon the telescope took its name.

The BOOMERanG team was led by [[Andrew E. Lange]] of [[Caltech]] and Paolo de Bernardis of the [[University of Rome La Sapienza]].<ref name="NYT_27Apr00">{{cite news |last=Glanz |first=James |date=27 April 2000 |title=Clearest Picture of Infant Universe Sees It All and Questions It, Too |url=https://www.nytimes.com/2000/04/27/us/clearest-picture-of-infant-universe-sees-it-all-and-questions-it-too.html?pagewanted=1 |work=[[The New York Times]] |access-date=2010-02-23}}</ref>

==Instrumentation==
The experiment uses [[bolometer]]s<ref name="Crill">{{cite journal|title=BOOMERANG: A Balloon-borne Millimeter Wave Telescope and Total Power Receiver for Mapping Anisotropy in the Cosmic Microwave Background|journal=[[Astrophysical Journal Supplement Series]]|volume=148|pages=527–541|doi=10.1086/376894|arxiv=astro-ph/0206254|last1=Crill|first1=B. P.|display-authors=etal|date=October 2003|issue=2|bibcode=2003ApJS..148..527C|s2cid=545283}}</ref> for  radiation detection. These bolometers are kept at a temperature of 0.27 [[kelvin]]. At this temperature the material has a very low heat capacity according to the [[Debye model|Debye law]], thus incoming microwave light will cause a large temperature change, proportional to the intensity of the incoming waves, which is measured with sensitive thermometers.

An off-axis 1.3-meter primary mirror<ref name="Crill"/> focuses the microwaves onto the focal plane, which consist of 16 horns. These horns, operating at 145&nbsp;GHz, 245&nbsp;GHz and 345&nbsp;GHz, are arranged into 8 pixels. Only a tiny fraction of the sky can be seen concurrently, so the telescope must rotate to scan the whole field of view.

==Results==
[[Image:Boomerang CMB.jpeg|thumb|200px|right|CMB Anisotropy measured by BOOMERanG]]
Together with experiments like the [[Saskatoon experiment]], [[Mobile Anisotropy Telescope|MAT/TOCO]], MAXIMA, and others, the BOOMERanG data from 1997 and 1998 determined the angular diameter distance to the surface of last scattering with high precision.  When combined with complementary data regarding the value of [[Hubble's law|Hubble's constant]], the Boomerang data determined the [[Friedmann equations|geometry of the Universe]] to be flat,<ref name="Nature_27Apr00"/> supporting the [[supernova]] evidence for the existence of [[dark energy]].  The 2003 flight of Boomerang resulted in extremely high [[signal-to-noise ratio]] maps of the CMB temperature anisotropy, and a measurement of the polarization of the [[Cosmic microwave background|CMB]].<ref name="MacTavish">{{cite journal|title=Cosmological Parameters from the 2003 Flight of BOOMERANG|date=August 2006|journal=[[Astrophysical Journal]]|volume=647|pages=799–812|last1=MacTavish|first1=C. J.|issue=2|display-authors=etal|doi=10.1086/505558|arxiv=astro-ph/0507503|bibcode=2006ApJ...647..799M|s2cid=18690323}}</ref>

==See also==
* [[BESS (experiment)]]

==References==
{{Reflist}}

==External links==
*[http://stratocat.com.ar/fichas-e/1998/MCM-19981229.htm report on the 1998 flight]
*[http://stratocat.com.ar/fichas-e/2003/MCM-20030106.htm report on the 2003 flight]
*[https://arxiv.org/abs/astro-ph/0209132v1 Polarization Sensitive Bolometric Detector]

{{CMB_experiments}}

[[Category:Cosmic microwave background experiments]]
[[Category:Balloon-borne telescopes]]
[[Category: Astronomical experiments in the Antarctic]]